With increasing popularity of handheld or portable devices such as iPhone®, Blackberry®, PDA (Personal Digital Assistants), cellular phones, and the like, the handheld devices are not only getting more powerful with sophisticated networking functionalities, but also getting more compact. While the portable devices can typically access ubiquitous information, such as e-mail, instant messages, VoIP (Voice over IP), video, photos, and the like, user interface (“UI”) devices for such portable devices become less intuitive and troublesome. Various currently available UI devices, such as touch-pads (PDAs and the iPhone®) or miniature keyboards (Blackberry®), are less user-friendly and intuitive. For example, touch pads allow larger screen areas than a keyboard and provide direct manipulation UI.
A problem associated with a typical touch pad is that the user's hand and fingers obscure the users' ability to see the screen when the users try to touch the pad. For example, selecting text using a finger over a portable screen can be cumbersome.
Another problem associated with a touch pad is that it is limited to two-dimensional implementation. For example, it can cause confusion to differentiate a scrolling gesture (touching the screen and moving your finger) from a navigation gesture (touching the screen).